GB1209660A - Process for electrodepositing organic coatings - Google Patents

Abstract

1,209,660. Electro-phoretic painting. GES: FUR ELEKTROCHEMISCHE MATERIALBESCHICHTUNG m.b.H. [trading as E.C.M. GES: FOR ELEKTROCHEMISCHE MATERIALBESCHICHTUNG m.b.H.K.G.]. Dec. 23, 1968 [Jan.17, 1968], No.61214/68. Heading C7B. An organic coating is electro-phoretically deposited on a conducting article, e.g. of Al, Fe, steel or with Au-plated surface connected as anode or cathode in an aqueous dispersion of a partly or completely reacted plastics material, adjusted to an electrical conductivity of 5, 00 to 100, 000 micro-mho/cm, to which has been added one or more anionic, cationic or amphoteric organic compounds having surface active properties and capable of forming a passive layer on the article, which develop an electrical resistance on the article within 25 seconds after the current density peak to reduce the density below 20% of the peak. Examples of organic compounds are alkali metal and amine soaps, alkyl and aryl and alkylaryl sulphonates, alkyl sulphates, alkali metal and ammonium salts and esters of sulphosuccinic acids and of sulphuric acid esters of castor oil, fatty acid condensates, casein, gelatine, lactalbumin, zein and gum arabic. Suitable dissociating substances for adjusting the required conductivity include soluble hydroxides (e.g. NaOH) carbonates (e.g. Na2 CO3), phosphates, chromates, halides (e.g. KF), cyanides (e.g. KCN), and salts of mono, di-, or polycarboxylic acids. Suitable plastics materials include polyalkylenes, polystyrenes, styrene copolymers, polyvinyl (idene) chloride, polyvinyl-actuates, -ethers and -carbazoles, F-containing polymers, polyacrylates, polyesters, alkyd resins, polyamides, polyamines, polyurethanes, polycarbonates, epoxy resins, formaldehyde resins and silicone resins. The plastics may still contain carboxyl, carbonyl, hydroxyl, amino or epoxide reactive groups. The dispersion may also contain hydrazine and peroxides as acceptors for oxygen and hydrogen respectively, pigments and/or dyestuffs. Powdered plastics material, e.g. a styrene-acrylonitrile copolymer of particle size 0À2 to 10 microns, may be used in making the dispersions, which may be adjusted to pH 12 with triethylamine. A polyol e.g. triglycol may be added to increase the B.P. of the dispersion. Diphenoxyethylformal or dibutylphthalate may be included as a plasticizer. The counterelectrode, e.g. cathode of 18 Cr-8Ni steel, may be the bath tank. The process is suitable for continuously coating strip, tubing or wire. The organic coating may be cured by baking at 80-200‹ C or treatment with electronic rays.